HD 120084

HD 120084
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Minor
Right ascension 13h 42m 39.201616s[1]
Declination +78° 03′ 51.979994″[1]
Apparent magnitude (V) 5.91[2]
Characteristics
Spectral type G7III[2]
B−V color index 1.000[2]
Astrometry
Radial velocity (Rv)−8.97±0.13[1] km/s
Proper motion (μ) RA: −64.900±0.031 mas/yr[1]
Dec.: 46.164±0.033 mas/yr[1]
Parallax (π)9.6277 ± 0.0258 mas[1]
Distance338.8 ± 0.9 ly
(103.9 ± 0.3 pc)
Absolute magnitude (MV)+0.96[2]
Details
Mass1.93[3] M☉
Radius7.81[3] R☉
Luminosity43.7[2] L☉
Surface gravity (log g)2.94±0.14[3] cgs
Temperature4,969±40[3] K
Metallicity [Fe/H]0.12±0.03[3] dex
Rotational velocity (v sin i)2.44[2] km/s
Other designations
BD+78°466, FK5 3090, HIP 66903, SAO 7876[4]
Database references
SIMBADdata

HD 120084 is a star with an orbiting exoplanet[2] in the northern constellation of Ursa Minor. With an apparent magnitude of 5.91,[2] it is just visible to the naked eye in suburban skies.[5] The distance to this system is 339 light years based on parallax measurements, but it is drifting closer to the Sun with a radial velocity of −9 km/s.[1]

This is an evolved G-type giant star, a yellow giant, with a stellar classification of G7III.[2] It has an effective temperature of around 4892 K, with around 1.9 times the mass, 43 times the luminosity and 8 times the radius of the Sun.[2][3]

Planetary system

A planet with at least 4.5 times the mass of Jupiter and a highly eccentric orbit (with an eccentricity of 0.66) was discovered by precisely measuring the radial velocity of the star in 2013. With an average distance of 4.5 AU from its star, this planet has one of the most eccentric orbits discovered.[2] In 2022, the inclination and true mass of HD 120084 b were measured via astrometry.[6]

The HD 120084 planetary system[6]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b 5.762+4.638
−0.285 MJ 		4.341+0.133
−0.155 		5.709+0.057
−0.088 		0.732±0.123 110.934+33.840
−60.717° 		—

References

  1. ^ a b c d e f Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b c d e f g h i j k Sato, Bun’ei; et al. (2013). "Planetary Companions to Three Evolved Intermediate-Mass Stars: HD 2952, HD 120084, and ω Serpentis". Publications of the Astronomical Society of Japan. 65 (4). 85. arXiv:1304.4328. Bibcode:2013PASJ...65...85S. doi:10.1093/pasj/65.4.85.
  3. ^ a b c d e f Andreasen, D. T.; et al. (2017), "SWEET-Cat update and FASMA A new minimization procedure for stellar parameters using high-quality spectra", Astronomy & Astrophysics, A69: 600, arXiv:1703.06671, Bibcode:2017A&A...600A..69A, doi:10.1051/0004-6361/201629967, S2CID 119534579
  4. ^ "HD 120084". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-07.
  5. ^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Sky Publishing Corporation. Archived from the original on 2014-03-31. Retrieved 2013-02-20.
  6. ^ a b Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.


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